43 lines
1.3 KiB
C++
43 lines
1.3 KiB
C++
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/*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* Copyright:
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* 2018, Danny Robson <danny@nerdcruft.net>
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*/
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#pragma once
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#include <functional>
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namespace cruft::search {
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/// Performs a linear search to discover the iterator corresponding to
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/// the value which minimises a function.
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///
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/// Useful as a mechanism to avoid possibly expensive comparison
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/// calculations; eg recomputing path distances when testing a series of
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/// possible routes.
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///
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/// The provided function will be invoked with the supplied argument pack
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/// as the first arguments and the dereferenced iterator as the final
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/// argument.
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template <typename InputT, typename FunctionT, typename ...Args>
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InputT
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minimises (InputT first, InputT last, FunctionT &&func, Args &&...args)
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{
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auto best_score = std::invoke (func, args..., *first);
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auto best_item = first;
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for (++first; first != last; ++first) {
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auto this_score = std::invoke (func, args..., *first);
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if (this_score < best_score) {
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best_score = this_score;
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best_item = first;
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}
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}
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return best_item;
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}
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}
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